This Oatey No.5 solder paste flux has a lead-free, petroleum-base formula that offers superior wetting properties for improved solder flow. It is effective on all metals excluding aluminum and stainless steel, and it's compatible with all common plumbing solder alloys. It won't turn your copper pipes green and is safe for use on potable water applications. The solder flux is certified NSF Standard 14 for cleaning effectiveness and Standard 61 for health effects. A brush is included for easy application.